Are we doing ourselves any favors repeating this 90% number?

[hfojvt]

8. here's the thing about polling

Imagine you had a bag with 310,000,000 marbles in it, and you want to know "what percentage of them are red and what percent are blue?"

The MOST accurate way, of course, would be to count every single marble in the bag, but good grief that would take a whole bunch of time.

Well, it turns out, that if you pull out, say 1,000 marbles at random, then the percentage of red marbles in that 1,000 is very, very likely to be the same as the percentage in the whole bag, and it is, of course, much easier to count 1,000 than it is to count 310,000,000.

They even have formulas for this, to calculate the "sample size" that would give you X% certainty of being correct given the size of your total population.

Because, clearly, a sample size of 3 or even of ten, is not going to be very accurate, but, in general, a sample size of 2,000 will be almost as accurate as a sample size of 10,000.